This invention relates to a primary storage device of a computer.
Traditional computer systems are disclosed in JP H11-272605 A, and others. To improve the processing performance of a computer system, it is desirable that all data be stored in the working set of the main memory. However, because of the limited capacity of the main memory, all data to be stored in the working set cannot be stored in the main memory. For this reason, the computer stores part of the data in a storage device and read the part of data from the storage device as necessary. Consequently, the access capability to the storage device is a bottle neck for the processing performance of the computer system.
Some approaches are known to cope with the above-mentioned bottleneck. For example, there is a technique that mounts a DRAM or a flash memory within a storage device to perform caching or tiering. You may refer to the paragraph 0019 of JP 2008-27383 A. There is another technique that uses a recently emerging flash memory device connectable to a PCIe bus to improve the performance. You may refer to the paragraph 0029 of US 2010/0252931 A.